Artificial blood vessels have been mainly used for the replacement of diseased blood vessels in living bodies or formation of bypasses. Therefore, artificial blood vessels are required to have good biocompatibility with hosts, non-toxicity or the like, be rarely deteriorated in living bodies and, therefore, tough, undergo a small volume of blood leakage, be antithrombogenic, not too expensive and the like.
Artificial blood vessels include artificial blood vessels made from cloths, artificial blood vessels made from polytetrafluoroethylene, artificial blood vessels derived from biomaterials, artificial blood vessels made from synthetic polymer materials and hybrid artificial blood vessels, and these artificial blood vessels are selected properly depending on intended use. For example, an artificial blood vessel made from a cloth has been mainly used as an artificial blood vessel for use in aortae having a large diameter (an inner diameter: 10 mm or more), and an artificial blood vessel made from a cloth and PTFE has been used frequently as an artificial blood vessel for use in arterial reconstruction in lower legs or the like which has a medium diameter (inner diameter: 6, 8 mm).
With respect to artificial blood vessels made from cloths, it has been demonstrated from long-term clinical tests that an artificial blood vessel made from polyester fibers is safe and practically useful as long as the artificial blood vessel has a medium or large diameter. However, when such an artificial blood vessel is used as an artificial blood vessel having a small diameter (an inner diameter: less than 6 mm), thrombi are formed in the artificial blood vessel and the artificial blood vessel cannot be kept in a patent state for a long period and, therefore, the practical usefulness of the artificial blood vessel for use as an artificial blood vessel for grafting applications is insufficient.
For the purpose of preventing the clogging and ensuring a sufficient patent state in the artificial blood vessel having a small diameter, a method of forming naps and/or loop-formed surface structures on the inner wall surface of the artificial blood vessel has been proposed (Japanese Patent Laid-open Publication No. 2005-124959), because the method can impart antithrombogenicity to the artificial blood vessel, in other words, enables rapid formation of endothelial cells on the inner wall surface of the artificial blood vessel.
However, when attempting to apply the technique disclosed in Japanese Patent Laid-open Publication No. 2005-124959 to an artificial blood vessel having a medium or small diameter, we found that the technique is not sufficient with respect to functions, properties and the like required for colonization of endothelial cells during grafting of the artificial blood vessel to a blood vessel having a medium or small diameter.
In those situations concerning the conventional artificial blood vessels, it could be helpful to provide an artificial blood vessel which can retain mechanical properties required for an artificial blood vessel and which rarely undergoes formation of thrombi and exhibits excellent cell adhesiveness when grafted into a blood vessel having a medium or small diameter.